Comments by the Submittor:

Concept for a Vascular Cartographic Scanning Nanodevice (9 July 2001)

The concept of function for this 1-micron in diameter nanodevice would be to serve as a vascular scanner which would traverse all arteries, veins, and capillaries to generate a very high resolution 3D map of a patients complete vascular system. It would also have the capability for superimposed maps (for instance showing the inside surfaces of all veins with superimposed plaque deposits or lesions to clearly discern what repairs, or material removal needs to be implemented).

Another function may be to measure vascular wall thickness and density of those walls. This information may, by inference, elucidate the elastic properties and strength of that wall.

This scanner could be introduced into the bloodstream via injection, patch, ingestion, or some other means of controlled infusion. It would be a totally autonomous unit. It would be linked to one or several external navigational beacons, and communications apparatus using the appropriate acoustic signals.

A possible deployment scenario could involve the release of a multitude of these devices working in different areas of the system in parallel. Each device would have its own assigned task and scanning region (a preset area overlap scan for all devices would guarantee full coverage) and all devices would be in constant communications with each other, either directly or through an external communications control center.

The physician would then be able to actually "cruise" the patients complete vascular system on a display to investigate any suspected problem areas, or gather information as to the general health of the system.

What follows is a summary of two envisaged aspects of the device.

Navigation:

A main reversible thruster, possibly a flow-through micro-fluidic jet system.

Two secondary reversible thrusters positioned at 90 degrees to and on either side of the main thruster.

A series of pivoting pulse-jets for fine-tuned positional control. These would be placed on the 45-degree faces of a 90-degree groove circumscribing the equator of the device.

The device would have an internal gyroscope working in conjunction with, and responding to an external positional reference grid, or a small-scale GPS setup. Perhaps general pathways it would follow (x,y,z coordinates) could be calculated in advance. Once internalized, it could then institute a self-centering program utilizing distance and orientation feedback sensors to ensure that it travels along the central axis of any sized portion of the vascular system.

Mapping:

The device is studded with multiple nested send/receive beacons.

A beacon would consist perhaps of a diamondoid rod array as its center, surrounded by a donut shaped ring of sensitive receivers. (Possibly, the devices body surface itself could serve this task).

Pulsed beams of an appropriate variety would emanate through the diamondoid rods to the target surface and reflect back to the receptor sites.

This operation would measure the distance from the central axis of the vein (for instance) as well as register the targets x,y,z coordinates as it would relate to the external reference grid.

Send/receive beacons would be distributed over the surface area of the device in a configuration that would ensure full 360-degree cross-sectional coverage of any vascular entity.

Pivoting mirrors could be incorporated at the tips of the diamondoid rods in order to facilitate full scanning coverage.

Predetermined response signatures from the data would differentiate between the inner surfaces of veins and plaque material.

Firstly, a map could be generated of only the interior surfaces of all arteries, veins, and capillaries. An additional map could then be created of the outer surfaces of the same entities. (By means of recalibration of the pulsed beam). A rendering of the surface topography of any plaque material could then be generated giving a detailed 3 dimensional view of the condition of the patient's entire vascular system.

As for the heart, it may have to be scanned in a different manner by a different type of device through virtue of its continuous motion and constant interior turbulence. Unless some form of temporary anchoring mechanism could be designed in, or the introduction of other specialized devices to aid in stabilizing the scanner so that it may obtain accurate data.